What is Chain ?
Chain is (noun) 1. a series of metal rings joined together She wore a gold chain round her neck. He stopped when the chain came off his bike. 2. a series of businesses such as stores, restaurants or hotels which belong to the same company a chain of hotels or a hotel chain She runs a chain of shoe shops. 3. a group of large mountains The Rockies are a chain of mountains running down from Canada through the western states. 4. a series of people, each buying another’s house There is a chain of six families involved, so the sale will take some time. (verb) to attach with a chain I chained my bike to the lamppost.
source: Easier English, Student Dictionary Upper Intermediate Level